Power failure recovery mechanism for a recording and reproducing device

ABSTRACT

The present invention relates to a power failure recovery mechanism for a recording and reproducing device such as a DVD player, wherein a recording indication information and a recovery pointer information is written in a non-volatile random access memory, while a recovery information is recorded on a record carrier such as a recordable optical disc. At a power-up operation, the recording indication information is used to determine a power failure and the pointer information is used to reproduce the recovery information in case of a determined power failure. Thus, the pointer information indicates the location of incremental recovery data structures on the record carrier, such that a recovery can be achieved after a power failure without requiring a restart of the entire recording.

The present invention relates to a power failure recovery method and arecording and reproducing device as defined in the preambles of claims 1and 13, respectively.

Computers and consumer electronics have been converging for years now, atendency accelerated by the development of the optical disc which openedthe way to the recent explosive growth of multimedia systems. As thisconvergence continues, the need is growing in the film industry for newhigh-capacity video discs, and in the computer industry for an equallyhigh-capacity ROM-discs.

DVD (Digital Versatile Disc) applications have been designed to provideconsumers with a high-quality multimedia format that will provide betterquality and more features than conventional VHS, SVHS or Laser Discbased products. DVD-Video applications require that data stored on thedisc follow a predetermined volume structure. A lead-in and lead-outarea are provided at the start and the end of the disc to facilitatesynchronization of the DVD players with the data stored on the disc. AVideo Manager file is used to store control information and videoobjects for the title menu. One or more Video Title Set (VTS) files areused to provide information on each title stored on the disc, includingcontrol data, video objects for the title menu, and video objects forthe title. All data for a video title must be stored in a directorylocated directly underneath the root directory.

During DVD recording, many recording data structures are kept in avolatile memory. These structures are necessary to be able to write aVideo Title Set Information (VTSI) at the end of the recording. The VTSIdescribes the nature of the VTS. According to the ISO 9660specifications, VTS may comprise a maximum of ten files. Without theVTSI, the entire recording is useless. Moreover, the menu creation makesuse of these data structures.

In case of a power failure during a recording operation, the datastructures stored in the volatile memory are lost. Therefore, a recoverymechanism is required.

Document JP-A-10 161 938 discloses a disc control apparatus with arecovery function, wherein a non-volatile SRAM (Static Random AccessMemory) having a smaller memory capacity than a write-back cache memoryis used. The optical data from a host is written into both the cachememory and the non-volatile SRAM. As the memory capacity of thenon-volatile SRAM is insufficient, batch forwarding of each optical datacurrently written in the non-volatile SRAM is done to a predetermineddisc back-up area on a disc drive. In case of a service interruption,the optical data stored in the cache memory is lost. However, thecontents of the non-volatile SRAM and disc back-up area can be used torestore the lost optical data. Thereby, a battery for holding the cachememory data is not required.

Furthermore, document JP-A-10 333 996 discloses a recording andreproducing device for recording on and reproducing from a recordingmedium. During a write-in process, a non-volatile memory stores an ID ofthe corresponding recording medium, using a flag. When write-in isinterrupted by a power failure, a failure generation judgement unitjudges the occurrence of a write-in error by comparing the ID of therecording medium and the flag stored in the non-volatile memory.

It is an object of the present invention to provide a power failuremechanism for a recording and reproducing device, by means of which arecovery can be achieved after a power failure during recording withoutrestarting the entire recording operation.

This object is achieved by a power failure recovery method according toclaim 1 and a recording and reproducing device according to claim 13.

Accordingly, by recording the recovery information on the record carrierat a location indicated by the pointer information, the recoveringinformation can be allocated to the actual recording information, andselectively reproduced when the recording indication informationindicates a power failure. An individual recovery information requiredfor recovering specific recording sectors can be obtained after a powerfailure, such that a restart of the entire recording operation is nolonger required.

According to an advantageous development, an additional pointer to alogical address at a beginning of a predetermined recording informationportion is written in the nonvolatile random access memory, wherein therecovery pointer is defined relative to the additional pointer. Inparticular, the predetermined recording information portion may be atitle set.

Preferably, the recording indication information is deleted when therecording operation has been finished and a title set information andmenu has been written. The recording indication information may be e.g.a recording flag.

According to another advantageous development, the recovery informationmay be a non-standardized private data stream. The private data streammay comprise a recovery sector for each recording cell, the recoverysector comprising all information necessary for recovering therespective cell after a power failure. In particular, the recoverysector may be multiplexed after the respective cell. Furthermore, therecovery pointer may point to the last recovery sector and each recoverysector may comprise a pointer information to the preceding recoverysector, the pointer information being used to reproduce the precedingrecovery sector. Then, the first recovery sector may comprise a flaginformation, wherein the recording step is performed until the flaginformation is deleted. The recovery pointer may be updated when arecovery sector has been recorded to the record carrier. The recoverysector may contain 2048 bytes, for example.

Further advantageous modifications of the invention are defined in thedependent claims.

In the following, the invention will be described in more detail withreference to the accompanying drawings, in which:

FIG. 1 shows a basic block diagram of an optical disc player accordingto a preferred embodiment of the present invention;

FIG. 2 shows storing fields in a non-volatile random access memoryrequired for the recovery mechanism;

FIG. 3 shows a recorded data sequence according to the preferredembodiment of the present invention;

FIG. 4 shows a basic flow diagram of a recording operation according tothe preferred embodiment; and

FIG. 5 shows a basic flow diagram of a recovery operation according tothe preferred embodiment.

The preferred embodiment will now be described on the basis of anoptical disc player, e.g. a DVD player as shown in FIG. 1.

FIG. 1 is a block diagram showing basic components of the optical discplayer.

According to FIG. 1, the optical disc player comprises a disc drive unit11 for recording on and reproducing from a recordable optical disc 20(e.g. a DVD+R/W disc or the like) by using a laser beam applied onto therecordable optical disc 20. Furthermore, the disc drive unit 11 isarranged to control a spindle motor 16 which rotates the recordableoptical disc 20. Furthermore, a volatile memory 14 such as a static ordynamic Random Access Memory (RAM) is provided for storing data whichhas been reproduced from the optical disc 20 or which is to be recordedon the optical disc 20. The volatile memory 14 is connected to an I/Ointerface 15 for inputting and outputting recording data and reproduceddata, respectively. Particularly, the I/O interface 15 may be a standardinterface such as an SCSI (Small Computer System Interface). Accordingto the preferred embodiment, a recovery control section 13 which may bearranged as a separate unit or which may be implemented in a systemprocessor section is provided for controlling the disc drive unit 11 soas to achieve a power failure recovery mechanism. The recovery controlsection 13 is connected to a Non-Volatile Random Access Memory (NVRAM)12 which may be arranged as a Static RAM (SRAM) made non-volatile byconnecting it to a constant power source such as a battery, or by anEEPROM (Electrically Erasable Programmable Read-Only-Memory) or a Flashmemory which save their contents when the power is turned off. The NVRAM12 is provided for storing recovery control information required after apower failure.

FIG. 2 shows corresponding storing fields or memory locations providedin the NVRAM 12 for storing the recovery control information. Inparticular, the recovery control information comprises a recording flag121 which is set when the recording and reproducing device (i.e. DVDplayer) starts a recording operation. The recording flag 121 is reset ordeleted when the recording has been finished and the VTSI and menu hasbeen written. Furthermore, the NVRAM 12 comprises a field for a titlesector pointer 122 which points to a logical address of an actual VTS orAudio Title Set (ATS) which is being recorded. Additionally, a storingfield for a recovery sector pointer 123 is provided, the recovery sectorpointer 123 being defined relative to the beginning or start address ofthe VTS or ATS.

The recorded area of the optical disc 20, provided between the lead-outarea and the lead-in area has a volume and file structure which complieswhich specific logic format standards, such as micro UDF (Universal DiscFormat) and ISO 9660 (International Standards Organization). The volumeand file structure consists of a volume management information area anda file area which includes a volume information file, and at least oneVTS and/or ATS. The volume management information stores contents whichare defined in the above described standard. The file area stores videodata, audio data, and data for managing the video data and the audiodata. That is, the VTS stores video, audio and sub-picture data, the ATSstores audio data and the file stores management data related to theVTSs and ATSs. Each of the title sets consists of at least one file andmaximum ten files. The title sets comprise video objects which consistsof a number of video cells comprising a plurality of GOPs (Group ofPictures). A movie story is a sequence of chapters which correspond toprograms. Thus, each program is defined as a group of video cells andeach object consists of a plurality of programs.

FIG. 3 shows a diagram representing the logic format of an optical discand the location of the pointer information and recovery informationwithin individual cells.

As can be gathered from FIG. 3, the logic format comprises at least oneVideo and/or Audio Title Set. The VTS comprise a plurality of videoobjects each of which comprises a plurality of video cells C1 to Cnconsisting of a plurality of GOPs (Group of Pictures). The video cellsC1 to Cn are multiplexed with corresponding recovery sectors R1 to Rnand corresponding pointers P2 to Pn. The first cell C1 is followed by astart flag SF and has no pointer allocated.

In the following, a recording operation of the recording and reproducingdevice shown in FIG. 1 is described with reference to the flow diagramdepicted in FIG. 4.

When the power is turned on and the optical disc 20 is loaded, aninitialization program is started and the recording flag 121 and theTitle Set Printer 122 are set in the NVRAM 12 under control of therecovery control section 13 (step S100). A control section (not shown)of the disc drive unit 11 reads the recording data from the volatilememory 14, which has been input from a host device (not shown) via theI/O interface 15. Then, required recording data structures according tothe required logic format of the optical disc, as shown in FIG. 3, aregenerated and stored in the volatile memory 14, in order to be suppliedto the disc drive unit 11 during the recording operation. Then, therecovery control section 13 generates a private data stream defined tostore incremental recording data structures on the disc. The content ofthe private data stream does not need to be standardized, as there is noneed for recovery to be supported on a different recording andreproducing device than the one on which the recording was made. Inparticular, one recovery sector per cell (1–2 minutes) is sufficient.Thus, for each of the cells C1 to Cn one recovery sector R1 to Rncomprising e.g. 2048 bytes is defined and contains all informationnecessary to recover the corresponding cell after the power failure. Asindicated in FIG. 3, each of the recovery sectors is multiplexed in therecording data stream after the entire cell has been written to thestream. However, there is no particular requirement regarding the actuallocation of the recovery sector with respect to the corresponding cell.In practice, it should be located as close as possible to thecorresponding cell within the multiplex constraints. Each of thepointers P2 to Pn is allocated to the corresponding one of the recoverysectors R1 to Rn and points to the previous or preceding recoverysector, relative to the beginning of the corresponding title set (VTS orATS), as indicated by the arrows shown in FIG. 3. The start flag SF isallocated to the first recovery sector R1 as a flag indicating the firstrecovery sector.

After the recording data for one cell and the corresponding recoverysector have been recorded on the optical disc 20 in step S101, therecovery sector pointer 123 is updated in the NVRAM 12 by the recoverycontrol section 13, so as to point to the latest recorded recoverysector (last recovery sector) (step S 102). Then, a check is performedin step S103 whether the end of a title set has been reached. If not,the flow returns to step S101 and the next cell is recorded togetherwith the corresponding recovery sector and pointer.

If the end of a title set has been detected in step S103, the title setpointer 122 is updated in the NVRAM 12 by the recovery control section13 (step S104). Thereafter, it is checked in step S105 whether the endof recording has been reached. If not, the flow returns to step S101 inorder to record the first cell C1 of the new title set together with thesector flag SF. If, on the other hand, the end of recording has beendetected, the VTSI is recorded in step S106. Then, the recording flag121 in the NVRAM 12 is cleared or reset by the recovery control section13 in step S107.

Thus, a recording overhead is generated by the recovery mechanism. Eachof the recovery sectors C1 to Cn contains e.g. 2048 kBit per minute(assuming that one cell has a duration of one minute). Thus, 273 bitsare recorded per second. Considering a typical recording rate of 3Mbit/s, this overhead can be regarded negligible.

In the following, a recovery operation after a power failure isdescribed with reference to FIG. 5.

According to FIG. 5, the recovery control section 13 reads the recordingflag 121 after the recordable optical disc 20 has been detected afterpower turn-on. Then, it is detected in step S202 whether the recordingflag is still set. If not, a recovery operation is not required, sincethe recording of the optical disc 20 has not been interrupted by a powerfailure. Thus, the recovery operation is stopped in step S210.

If it is detected in step S202 that the recording flag is still set, aninterruption of the recording due to a power failure is assumed and thetitle set pointer 122 and the recovery sector pointer 123 are read fromthe NVRAM 12 by the recovery control section 13. Accordingly, theposition of the last recovery sector before the power failure can bederived from the pointer information stored in the NVRAM 12. Then, therecovery control section 13 controls the disc drive unit 11 so as toreproduce the respective recovery sector indicated by the pointerinformation and loads the recovery sector into the volatile memory 14(step S204). Based on the loaded recovery sector, the recovery controlsection 13 detects the recorded pointer Pi to the preceding recoverysector R(i−1) in step S205.

Alternatively, it may be necessary to load all recovery sectors at once,depending on the internal RTA data structures.

Based on the detected pointer Pi, the previous recovery sector R(i−1) isretrieved from the reproduced information. In step S206, it is checkedon the basis of the sector flag SF whether the first recovery sector hasbeen reached. If not, the flow returns to step S204 in order to load orderive the next recovery sector.

If the first recovery sector has been detected in step S206, theinternal data structures are reconstructed in step S207 based on theobtained recovery information. Then, the VTSI and menu can be updated instep S208 such that a cell accurate recovery has been performed. Whenthe recovery has been completed, the recording flag 121 in the NVRAM 12is cleared or reset by the recovery control section 13 in step S209.

The recovery time can be estimated as follows. Assuming a cell durationof one minute and a recovery duration of 0.5 to 1 seconds for each cell,a recording of two hours will take 60 to 120 seconds to be recovered.This duration does not include the time needed to generate the menu.

In summary, a recovery mechanism is proposed which provides a recoveryfrom power failure. To achieve this, a recovery stream is defined forrecording incremental data structures on the record carrier. Based onthe recording flag 121 and the pointer information stored in the NVRAM12, the recorded recovery data structures can be retrieved. Therecording flag 121 is set at the beginning of the recording, and thepointer information is updated during the recording of the recoveryinformation. Thus, a recovery after a power failure during recording canbe achieved without requiring a restart of the entire recording.

While the invention has been described with reference to a preferredembodiment, it is to be understood, that this is not a limiting example.Thus, various modifications may become apparent to those skilled in theart without departing from the scope of the invention, as defined in theappended claims. In particular, the invention is not limited to thespecific recording data structure shown in FIG. 3 and the recordableoptical disc. The invention is applicable to any recordable recordcarrier or medium. Any kind of recording structure of the recoveryinformation can be implemented as long as the recovery information canbe retrieved on the basis of the pointer information stored in thenon-volatile memory of the recording and reproducing device. Inparticular, the pointer information may comprise a single absolutepointer which points to the recovery information.

1. A power failure recovery method for a record carrier recording andreproducing device (10) having a non-volatile random access memory (12)characterized by the steps of: a) writing a recording indicationinformation and a recovery pointer information in said non-volatilerandom access memory (12) during a recording operation; b) recording arecovery information on the record carrier (20) at a location indicatedby said pointer information; c) deleting said recording indicationinformation at the end of said recording operation; d) reproducing saidrecovery information from said record carrier (20) by using saidrecovery pointer information, if said recording indication informationis detected at a power-up operation; and e) performing a recoveryoperation based on said reproduced recovery information.
 2. A methodaccording to claim 1, characterized by the step of writing a pointer toa logical address of the beginning of a predetermined recordinginformation portion, in said non-volatile random access memory (12),wherein said recovery pointer is defined relative to said pointer.
 3. Amethod according to claim 2, characterized in that said predeterminedrecording information portion is a title set.
 4. A method according toclaim 1, characterized in that said recording indication information(121) is deleted when said recording operation has been finished and atitle set information and menu has been written.
 5. A method accordingto claim 1, characterized in that said recording indication informationis a recording flag (121).
 6. A method according to claim 1,characterized in that said recovery information is a non-standardizedprivate data stream.
 7. A method according to claim 6, characterized inthat said private data stream comprises a recovery sector for each cell,said recovery sector comprising all information necessary for recoveringthe respective cell after power failure.
 8. A method according to claim7, characterized in that said recovery sector is multiplexed after saidrespective cell.
 9. A method according to claim 7, characterized in thatsaid recovery pointer points to the last recovery sector and eachrecovery sector comprises a pointer information to the precedingrecovery sector, said pointer information being used to reproduce saidpreceding recovery sector.
 10. A method according to claim 7,characterized in that the first recovery sector comprises a flaginformation, wherein said recording step is performed until said flaginformation is detected.
 11. A method according to claim 7,characterized in that said recovery pointer is updated when a recoverysector has been recorded to the record carrier (20).
 12. A methodrecording to claim 7, characterized in that said recovery sectorcontains 2048 bytes.
 13. A recording and reproducing device forrecording on and reproducing from a record carrier (20), said devicecomprising: recording and reproducing means (11) for recording on andreproducing from said record carrier (20); and a non-volatile randomaccess memory (12), characterized by writing means (13) for writing arecording indication information (121) and a pointer information intosaid non-volatile random access memory (12) during a recordingoperation; deleting means (13) for deleting said recording indicationinformation (121) at the end of said recording operation; anddetermining means (13) for determining whether said recording indicationinformation (121) is deleted or not; wherein said recording andreproducing means (11) is arranged to reproduce said recoveryinformation from said record carrier (20) by using said pointerinformation in response to the output of said determining means (13).14. A device according to claim 13, said characterized in that saidrecord carrier is a recordable optical disc (20).
 15. A device accordingto claim 13, characterized in that said recovery pointer points to alast recovery sector of said recovery information and said recording andreproducing means (11) is controlled to reproduce said recoveryinformation by using a pointer information contained in each recoverysector and pointing to the preceding recovery sector.
 16. A deviceaccording to claim 15, characterized in that said recording andreproducing means (11) is controlled to reproduce said recoveryinformation until a flag information indicating the first recoverysector has been detected.
 17. A device according to claim 13,characterized in that said recording and reproducing means (11) isarranged to multiplex said recovery information with a recordinginformation during said recording operation.
 18. A device according toclaim 13, characterized in that said recording and reproducing device isa DVD player.